package simple15.observer;

import java.util.ArrayList;
import java.util.List;

public abstract class Attentions {
//    关注客户列表
    protected List<Observer> observers = new ArrayList<>();
//    关注顾客
    public void add(Observer observer){
        observers.add(observer);
    }
//    取消关注
    public void remove(Observer observer){
        observers.remove(observer);
    }
//    发通知
    public abstract void notifyObservers();
}
